Reuters (http://reut.rs/WYfXDS) said the scene at state oil company Pemex's headquarters was one of chaos and confusion.
Search and rescue workers picked through debris while investigators sifted through shattered glass and concrete at the bottom of the building to try to find what caused the blast. It was not clear how many people might still be trapped inside.
Read more about the incident at http://reut.rs/WYfXDS.
For more on firefighters' roles in urban search and rescue operations in such instances as the Haiti earthquake, consider California Task Force Rescues, New York Task Force 1 Response, Confined Space Rescue : Why Operations Fail, and BREATHING AIR SYSTEMS FOR CONFINED SPACE RESCUE.